Posted in Web Thoracic Outlet Syndrome: Symptoms, Causes, Diagnosis … January 25, 2021 Thoracic Outlet Syndrome Causes and Risk Factors. There are several causes: Injuries: Whiplash, a broken collarbone, or other injury can leave scar tissue and inflammation. Poor posture: When your … https://www.webmd.com/brain/thoracic-outlet-syndrome